This invention pertains to a furnace having a generally cylindrical combustion chamber with an improved single port inshot target burner.
The problem faced was the design of a burner capable of satisfactorily firing into a compact cylindrical combustion chamber with a helical heat exchanger extending from an end thereof. Conventional target burners were tried but they did not provide sufficiently compact flames which would not overheat the combustion chamber or be quenched. If the flame were quenched, there would be incomplete combustion and possible formation of soot.
Most conventional target burner systems with high release rates are forced air systems which result in positive heat exchanger pressure. However, the inventors determined that an induced draft system was preferable because it would result in negative pressure in the heat exchanger. If there were a hole in the heat exchanger, combustion products would not leak into the conditioned indoor air. The use of an induced draft system posed stability, air/fuel ratio and mixing problems that had to be overcome.
An object of the present invention is to provide a furnace utilizing a compact generally cylindrical combustion chamber having a heat exchanger tail pipe extending therefrom with a single port inshot target burner operable with an induced air blower system that produces a negative pressure within the combustion chamber.
Another object of this invention is to provide an improved single port inshot target burner for use within a compact generally cylindrical heat exchanger having a negative pressure induced therein, said target burner having a flame retention ring in the outlet end thereof for better attaching the flame to the outer surface of the flame retention ring and thereby improve flame lifting characteristics.
Still another object of this invention is to provide an improved single port inshot target burner with a frustro-conical member encircling the target burner for directing air toward the outlet end of the target burner for enhancing the combustion process.
Other objects and advantages of the present invention will be made more apparent hereinafter.